1. Field of the Invention
The present invention relates generally to cable modems and data transmission in cable modem networks. More specifically, it relates to rapid re-provisioning of a cable modem on demand without having to go through a start-up procedure.
2. Discussion of Related Art
Since the late 1980's the cable TV industry has been upgrading its signal distribution and transmission infrastructure. In many cable television markets, the infrastructure and topology of cable systems now include fiber optics as part of its signal transmission component. The use of fiber optics has accelerated the pace at which the cable industry has taken advantage of the inherent two-way communication capability of cable systems. The cable industry is now poised to develop reliable and efficient two-way transmission of digital data over its cable lines at speeds orders of magnitude faster than those available through telephone lines, thereby allowing its subscribers to access digital data for uses ranging from Internet access to cable commuting. While cable TV systems have always had the ability to send data downstream, i.e. from a cable TV hub, described below, to cable modems in people's homes, cable TV systems can now send data upstream, i.e. from individual cable modems to a hub. This new upstream data transmission capability enabled cable companies to use set-top cable boxes and provided subscribers with “pay-per-view” functionality, i.e. a service allowing subscribers to send a signal to the cable system indicating that they want to see a certain program.
FIG. 1 is a block diagram of a two-way hybrid fiber-coaxial (HFC) cable system including cable modems and a network management station. The main distribution component of an HFC cable system is a primary (or secondary) hub 102 which can typically service about 40,000 subscribers or end-users. Hub 102 contains several components of which two, relevant to this discussion, are shown in FIG. 1. In one configuration, one of the components is a cable modem termination system, or CMTS, 104 needed when transmitting data (sending it downstream to users) and receiving data (receiving upstream data originating from users) using cable modems, shown as boxes 106, 108, 110, and 112. In another configuration, the CMTS can be outside the hub and located in a fiber node. The other component is a fiber transceiver 114 used to convert electrical signals to optical signals for transmission over a fiber optic cable 116. Fiber optic cable 116 can typically run for as long as 100 km and is used to carry data (in one direction) for most of the distance between hub 102 to a neighborhood cable TV plant 117. More specifically, fiber optic cable 116 is a pair of cables—each one carrying data in one direction. When the data reaches a particular neighborhood cable TV plant 117, a fiber node 118 converts the data so that it can be transmitted as electrical signals over a conventional coaxial cable 120, also referred to as a trunk line. Fiber transceiver 114 can be replaced by an RF translator or other device for converting to broadband or over-the-air (wireless) frequencies, and any antenna device (wireless radiator). Fiber optic cable 116 can also be any wireless link, over-the-air connection, or other free space optical link. Fiber node 118 can also be an RF translator or other device or an antenna device (wireless radiator) from converting from broadband or over-the-air (wireless) frequencies back to frequencies compatible with a cable modem. Fiber transceiver 114 can be integrated into the CMTS or a cable modem device. Many of these substitutions would effectively leave the topology of the cable modem network unchanged. Hub 102 can typically support up to 80 fiber nodes and each fiber node can support up to 500 or more subscribers. Thus, there are normally multiple fiber optic cables emanating from hub 102 to an equal number of fiber nodes. In addition, the number of subscribers as well as fiber capacity is currently increasing due to dense wave-division multiplexing technology. DWDM is a technique for transmitting on more than one wavelength of light on the same fiber.
The primary functions of CMTS 104 are (1) interfacing to a two-way data communications network; (2) providing appropriate media access control or MAC level packet headers (described below) for data on the RF interface of a cable system; and (3) modulating and demodulating the data to and from the cable system.
Cable TV (CTV) taps 122 and 124 are used to distribute a data signal to individual cable modems 106 and 110 (from CTV tap 124) and modems 108 and 112 (from CTV tap 122). Two-way cable TV amplifiers 126 and 128 are used to amplify signals as they are carried over coaxial cable 120. Data can be received by the cable modems shown (each CTV tap can have output cables servicing multiple cable modems) and transmitted back to hub 102. In cable systems, digital data is carried over radio frequency (RF) carrier signals. Cable modems are devices that modulate a digital signal to an RF signal and demodulate an RF signal to a digital signal for transmission over a coaxial cable. This modulation/demodulation is done at two points: by a cable modem at the subscriber's home and by CMTS 104 located at hub 102. If CMTS 104 receives digital data, for example from the Internet, it converts the digital data to a modulated RF signal which is carried over the fiber and coaxial lines to the subscriber premises. A cable modem then demodulates the RF signal and feeds the digital data to a computer (not shown). On the return path, the operations are reversed. The digital data is fed to the cable modem which converts it to a modulated RF signal. Once CMTS 104 receives the RF signal, it demodulates it and transmits the digital data to an external source. It should be noted that several of the components described above, including CTV 122 and 124 and amplifier 126, can be replaced or eliminated depending on the necessary topology or requirements of a particular cable modem network.
Data packets are addressed to specific modems or to a hub (if sent upstream) by a MAC layer 130 in CMTS 104 at hub 102 (there is also a MAC addressing component, not shown, in the cable modems that encapsulate data with a header containing the address of the hub when data is being sent upstream). CMTS 104 has a physical layer 132 that is responsible for keeping a list of modem addresses and encapsulating data with appropriate address of its destination. MAC layer 130 receives data packets from a Data Network Interface (not shown) in hub 102. The main purpose of MAC layer 130 is to encapsulate a data packet within a MAC header according to the DOCSIS standard for transmission of data. This standard is currently a draft recommendation (J.isc Annex B) which has been publicly presented to Study Group 9 of the ITU in October 1997, and is known to a person in the cable modem data communication field. MAC layer 130 contains the necessary logic to encapsulate data with the appropriate MAC addresses of the cable modems on the system. Each cable modem on the system has its own MAC address. Whenever a new cable modem is installed, its address must be registered with MAC layer 130. The MAC address is necessary to distinguish data going from the cable modems since all modems share a common upstream path, and so that CMTS 104 knows where to send data. Thus, data packets, regardless of format, must be mapped to a particular MAC address. MAC layer 130 is also responsible for sending out polling messages as part of the link protocol between the CMTS and the cable modems that is necessary to maintain a communication connection between the two.
Cable modems receive configuration files and are provisioned based on data in such configuration files. Provisioning a cable modem can be defined as reconfiguring the operational parameters of the modem. By provisioning a cable modem, the network is establishing the allocation of resources to a particular cable modem in a cable modem network. A DOCSIS-compliant cable modem receives a configuration file during initial provisioning (described below) which contains data such as ISP, quality of service, data rate, number of PCs that can use the modem, and similar data. Current methods of provisioning a cable modem take more time than is desirable (up to four minutes) and is disruptive to the customer. Cable modem users typically do not want to wait that long for a provisioning change in their modem. For example, telephone customers can now change carriers for a particular call by dialing a special number (e.g., 10-10-321) and the change in service is almost instantaneous. Presently, if a customer wants a provisioning change, the cable modem must be reloaded or rebooted, thus taking the cable modem offline.
There are a number of reasons why a cable modem user, a cable network operator, or a cable network ISP may want to re-provision a cable modem. For example, a user may want to receive or transmit an unusually large file and, therefore, will want to increase the bandwidth of the downstream or upstream carrier to accommodate the large file but then return to the normal bandwidth. In another example, a user may be playing a game online and may want to use a different ISP for better performance. The user may want to switch to a premium service from standard service for a limited time (e.g., for a few minutes, hours, a day) or for a single transmission. A cable network operator or ISP may want to provision a particular cable modem because that modem experienced an unexpected or unexplainable fault and cannot be recovered using normal methods. For example, a problematic cable modem may not be rebootable or restartable using routine hardware approaches of powering up the modem. In another example, the cable modem may have been tampered with by the user and can only be repaired by the network operator by re-provisioning the cable modem. However, in some cases re-provisioning the cable modem is not possible using the typical route of reloading or rebooting the cable modem using the normal DOCSIS approach. These normal approaches involve sending a Layer 3 IP system command, such as an SNMP command, to the cable modem.
Therefore, it would be desirable to have a more rapid and less disruptive process for re-provisioning a customer cable modem that does not take the cable modem offline or cause it to reboot. It would be desirable to do so by using existing tools and commands in the existing standard. Furthermore, it would be desirable to allow a cable modem customer to provision a modem on demand to suit the customer's needs.